Gas purifying material free from hydrogen sulphide generating organisms



UNlTED STATES rrur GAS PG MATERIAL FREE FROM I HYDROGEN SULPHIDE GENERATING R- GANISMS Gilbert E. Seil, Cy'nwyd, Pa., assignor to E. J.

Lavino and Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Application February 27, 1939,

Y Serial No. 258,853

1 Claim. (01. 252191) 'Ihis invention relates to gas purifying mareaches the point at which it is no longer ecoterlals such as unmixed powdered gas purifying nomical to cont ue this box in service, the bOX materials, and gas purifying materials mixed is taken from the series, and the fouled material with wood shavings. In. the latter class of mais removed from the box and revivified or it-- terials the wood shavings act as a flufling or dismay be revivified in place- B 2 then e- 5 tributing agent for the powdered material. In comes the first box of the series, and a box the nomenclature of the art, gas purifying macontaining new or'revivified ferric oxide material terials of the first class are called unmixed is inserted as the last box in the series. oxides or simply oxides, and gas purifying The fouled g Purifying material levivified materials of the second class'are called mixed by bringing it into contact with air either in 10 oxides or sponges. The terms clean gas the box or after removal from the box. In conand foul gas are used herein in conformity tact with oxygen the ferric sulphide is oxidized with their usual meanings in this field, namely; to ferric oxide and elemental sulphur, and the refi a s is gas containing no hydrogen sulvivified material may be replaced inthe system phide, while gas containing'hydrogen sulphide is for further fouling. When the sulphur in the 15 called foul gas. The term traces indicates material is built up to a. point at which it is the definite presence of HZS but in'amounts less no longer economical to revivify and reuse the than 5 grains per 100 cubic feet of gas, and it material, it is discarded. must be borne in mind that gas companies are Individual plants may vary considerably from 5 not permitted to distribute gas containing traces the procedure outlined above, but for the purof Has to the consumers, and for this reason poses of this description it is sufiicient to say the s going from the Pu a o y tem 190 that it is general practice to'arrange the purithe holders must be clean. Gas purifying mafication series sotha-t the final box contains puris which have been subjected to sulphidin fying material substantially free of ferric sul- 5 are known as fouled oxides or fouled sponges. phide, so that by passing the gas through this Revivification is h p s f r c fyin a box the last traces of H2S are removed.

fouled ferric oxidematerial by contact with oxy- V rious gas plants have found that at times gen, and materials reactified in this fashion are the passage of clean gas through a box conknown as revivified materials. taining purifying material which'has not pre- 0119 method of e ov yd sulphide viously been subjected to sulphiding will cause from a gaseous niixture is to pass the mixture the gas to pick-up small amounts of hydrogen through Series Of purifi r known as -b sulphide. Gas plants are not permitted to dis- The y boxes u y C a a ferric Oxide tribute gas'containing H25, and the presence of sp n and the H28 is r ve y causing it to even the slightest trace of H25 in the gas leaving react with the ferric oxide, forming ferric sul-. t final x of th purification system gives phide and water. 111' following this method it is i t Serious prblem, I the general Pract ce to P ss the S 1 Examination of the purification materials in mg t H28 through 8- S r es Of 1311166 01756111 boxes which exhibit the tendency to foul the clean boxes. The first box removes most o the gas when the purification material is substanw y %.to the Seco bOX the Second tially free of ferric sulphide and sulphur revealed w I and third boxes) removes the balance, and the the presence of molds or fungi which live and fi a bOX is a S y measure to insure the grow in the atmosphere of the box, and which are P b c cc fHzs in the s going to e capable of generating hydrogen sulphide. The .holders' for distribution. For examp e, the hydrogen sulphide thus generated is picked-up lowing results are typical in a four bOX System, by and cgntaminates 'the gas in its passage the HES being'expressed in grains per .100 cubic through the box, feet of gas: Several of the molds' which have caused fouling of the gas in different gas plants have been ms atinlet His atoutlet definitely identified. Among others,'I can 'list the Fungi Imperfecti 'Irichoderma of the order 59 Monillales, the Fungi Imperfecti Repens and Macrosporum of the order Rhinotrichum; sev-' eral species of the Fungi Graphium,'and the r f V 5 Phycomycete Mucor of the order Mucorales. M When the accumulated sulphur in Box No. 1 Trichoderma is acommon soil mold with marked cellulose decomposing tendencies. Mucor is a very common saprophyte. Both'Repens and Macrosporum haue been observed growing on decaying soft woods. Probably many other organisms have similar characteristics to those mentioned. Troublesome fungi or the spores thereof apparently are carried by the wood shavings as hosts or the wood fiufiing agent is inoculated with. them. But under the dry box operating conditions, they seem to come out of spore form and assume active growth and frui-- oxide for reaction and at the-same time reducingthe pressure. needed to force the gas through the box. In View of the characteristics of the organisms mentioned, it is probable that they are introduced into the sponge with the wood shavings.

It is a major object of my invention to eliminate the above described difiiculty, and to that end I provide a gas purifying material which is treated before installation in the purification system, whereby it is caused'to be in a sterilized condition as regards hydrogen sulphide generating organisms. To accomplish this purpose I prepare either an oxide or a sponge purifying material to which has been added a small amount of sterilization agent. Theseagents may be chosen for any or all of qualities such as fungicidal action and germicidal 'action, for example from the group in which the desired qualities arederived from the.

phenol value such as phenol, tar acid, cresole,' sodium phenolate, sodium cresolate, etc. Suitable sterilization agents may also be obtained from the group in which the desired qualities are de rived by theliberation-of halogens, such as sodium hypochlorite', calcium hypochlorite, etc.

I have foimdthat commercial tar acid, when used in quantities as small as 0.25 pound per 10 bushels of sponge (that is approximately 0.1% by weight) effectively eliminates the activities of the H38 generating organisms. Other steriliza tion agents can be used in correspondingly small amounts. By way of example, commercial tar acid contains to of phenols. stantially pure phenol commercial product known as 39 C. Minimum melting point phenol is three times as effective as tar acid, and is therefore effective when used in one-third the amount;

The sterilization agent may be added to the mixture of ,oxide and wood shavings: when the sponge is being prepared, or it. may be added to the oxide before'shipment to the point of spo e manufacture. The latter method offers a method of providing an oxide which will produce sponge free from hydrogensulphide generating organisms for such plants as prefer to mixtheir own sponge. I

The fact that certain living organisms can exist in an atmosphere of gas containing HzS has been known for sometime. In my U. S. Patent No. 1,701,825,; granted February 12, 1929, I describe a method of gas purification which depends upon the ability of 'certain bacteria, such as the Thiobacz'llus thiopacus and the Thiobacillus denitrificans, to oxidize hydrogen sulphide to A subsulphur or sulphuric acid or both, and water. The gas containing HzS is purified by contact with a medium containing bacteria capable of oxidizing H23 and containing means for supporting the life processes of said bacteria.

I prefer to practice the present invention in conjunction with my U. S. Patent No. 1,818,871, granted August 11, 1931., The invention is of course applicable to all gas purifying materials of the type'referred to, and I do not restrict 1r myself to the method of practicing the invention which I describe below.

In my U. s. Patent No. 1,818,871 I describe the production of a ferric oxide gas purifying material by heating a mixture of an iron oxide 15 bearing material with an alkali bearing material to a temperature of 760 C. to 1200 C., forming the alkali ferrite. Preferably I heat a mixture of pyrites cinder and soda ash to a temperature of approximately 954 C. (1750 F.) forming sodium 211 ferrite. The sodium ferrite is decomposed by not water into chemically active ferric oxide and caustic soda solution, the soda solution being drained or filtered from the ferric oxide, and the ferric oxide beingsubstantially freed ofsoda by 25 subsequent washing with .fresh water. The soda thu's recovered is returned to the process by mixing it with fresh pyrites cinder. The chemically active iron oxide is preferably. wet ground in suitable equipment so that about 90% passes. 30

a Bureau of Standards N0. 325 screen, and I prefer to carry out this grinding operation in a cylindrical ball mill. The slurry leaving the ball mill may be dried at a temperature not exceeding 300 F. and sold as a gas purifying oxide,

or it may be used, with additional water if necessary, for coating wood shavings to produce a sporige of given ferric oxide content.

In one method of practicing the presentinvention I add the sterilization agent .in the required proportions to the oxide entering the ball mill and in this way provide a treated material which may either be dried for use as oxide or made into sponge. In another method, when the slurry-is to be used for the production of sponge 5 -I may add the desired amount of sterilization agent to the slurry after it leaves the ball mill, but before it is mixed with the wood shavings. In a third method, when sponge is made in a batch mixer, the sterilization agent required for the lo batch can be added to the mixer with the oxide, shavings, and water. a

The amount of sterilization agent used depends upon its effectiveness in eliminating the activities have explained that-.025 pound of tar acid per bushelof sponge is sufficient. If the sponge'is to contain 10 pounds of oxide. dry basis, per bushel,

I can add the tax acid in the proportion of .025

pound of tar acid per 10 pounds of dry oxide, I either to the oxide entering the ball mill or to the slurryleaving the ball mill. The proportion is of course adjusted with the amount of oxide,

dry basis, used per bushel of sponge. If the sponge is made in a batch mixer I can add the tar acid to each batch in quantity sufflcient to provide 0.025 pound of tar acid per bushel of finished spon e.

In addition to the difliculties I have mentioned 10 arising from the contamination of the gas by hydrogen sulphide generating organisms there is a further purely physical efifect of the organisms on the purification system. The organisms,

' of hydrogen sulphide generating organisms? I '55 as theygrow, fill in the pores or voids through i which the gas normally passes and introduce a tight soggy layer. The result is an area resistant to the flow of gas, which forces the gas to take preferential paths through the purifying material. As a result of this preferential flow, portions of the purifying material will be only' partially effective, and the service rendered by the box is reduced in proportion to the eifectiveness of the gas purifying material.

Having thus described and exemplified my incellulosic flumng medium such as wood shavings and containing a germicideconsisting of .025

pound of tar acid per bushel of sponge or 0.25% by weight of the dry oxide disseminated throughout the sponge.

' GILBERT E. SEIL. 

